1. Field of the Invention
The present invention relates to a pitch angular velocity correction value calculation device, an attitude angle calculation device, and a method for calculating a pitch angular velocity correction value.
2. Description of the Related Art
Objects such as vehicles are each equipped with a rate gyro for calculating attitude angles of the object. The rate gyro generates offset voltage (hereinafter referred to as “offset”) depending on a change in temperature or humidity, for example. An offset correction device for onboard gyros has been known, which accurately corrects the offset of a rate gyro (for example, refer to Japanese Patent Application Laid-open No. 2011-191243 A). This technique determines a mean value of a prescribed period of angular velocity, during a period in which an angular velocity determined by a yaw rate gyro is below a prescribed angular velocity, from among angular velocities determined by a pitch rate gyro, and performs correction by using the mean value as an offset of the pitch rate gyro.
The technique described in Japanese Patent Application Laid-open No. 2011-191243 A calculates an offset using the angular velocity of a pitch rate during a period in which the pitch rate is not affected by a yaw rate, and corrects the offset of the pitch rate gyro. However, when a vehicle travels on a slope for example, a component from vertical movement of the vehicle is superimposed on the pitch rate gyro. Thus, the technique described in Japanese Patent Application Laid-open No. 2011-191243 A has room for improvement in the accuracy of the offset correction of a pitch rate gyro.